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gh-89519: Remove classmethod descriptor chaining, deprecated since 3.11#110163

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rhettinger merged 6 commits intopython:mainfrom
rhettinger:remove_classmethod_descriptor_chaining
Oct 27, 2023
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gh-89519: Remove classmethod descriptor chaining, deprecated since 3.11#110163
rhettinger merged 6 commits intopython:mainfrom
rhettinger:remove_classmethod_descriptor_chaining

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@rhettinger rhettinger commented Sep 30, 2023 •
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@rhettinger rhettinger added type-bug An unexpected behavior, bug, or error 3.13 bugs and security fixes labels Sep 30, 2023
@bedevere-app bedevere-app bot mentioned this pull request Sep 30, 2023
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rhettinger commented Oct 1, 2023

I'm still working on the doctest for the descriptor howto. It looks like the classmethod emulation is imperfect after the classproperty has been removed.

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KevinMGranger commented Oct 23, 2023

Will this break the pattern described as an alternative to abc.abstractclassmethod?

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rhettinger commented Oct 24, 2023

@KevinMGranger The examples for combining abstractmethod with classmethod and staticmethod will still work. This is tested in test_abstractclassmethod_basics() in Lib/test/test_abc. Also, here's a live demonstration:

% ./python.exe
Python 3.13.0a0 (heads/remove_classmethod_descriptor_chaining:8336eb0b87, Oct 24 2023, 14:41:05) [Clang 15.0.0 (clang-1500.0.40.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from abc import ABC, abstractmethod
>>> class C(ABC):
...     @classmethod
...     @abstractmethod
...     def my_abstract_classmethod(cls, arg):
...         ...
...
>>> C()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Can't instantiate abstract class C without an implementation for abstract method 'my_abstract_classmethod'

Note, these examples have worked since Python 3.3 which was long before the broken descriptor chaining arrived in Python 3.9. So, they are independent of the change being reverted. Thanks for asking.

facebook-github-bot pushed a commit to facebookincubator/cinder that referenced this pull request Oct 25, 2023
@itamaro @facebook-github-bot
GH-89519: Remove classmethod descriptor chaining, deprecated since 3.…
6f02c7f 
…11 (#110163)

Summary: backporting [Raymond Hettinger's `remove_classmethod_descriptor_chaining` branch](https://github.com/rhettinger/cpython/tree/remove_classmethod_descriptor_chaining) (pending upstream PR [GH-110163](python/cpython#110163)), part of upstream issue [GH-89519](python/cpython#89519)

Reviewed By: swtaarrs

Differential Revision: D50534886

fbshipit-source-id: 05b29193ce220f0d91fd0df8d5cef34d7e923456
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itamaro commented Oct 26, 2023

Looking forward to see this getting merged!

fwiw, I ran into an issue related to classmethod descriptor chaining in the Meta codebase -- some code (that was written for Python 3.8, doing a bunch of signature and type inspection of decorated methods) started breaking under Python 3.10.
I backported the deprecation from 3.11 and this removal into Cinder 3.10, and it resolved the issue.

If it helps with confidence in the removal - this PR (cleanly backported to 3.10) is running in production (in Instagram and other Meta Python services), after all internal test suites passed (including the full Instagram test suite).

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rhettinger commented Oct 27, 2023

@itamaro Thank you for your comment. Indeed, it does increase the confidence in the PR.

@rhettinger rhettinger added the 🔨 test-with-buildbots Test PR w/ buildbots; report in status section label Oct 27, 2023
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bedevere-bot commented Oct 27, 2023

🤖 New build scheduled with the buildbot fleet by @rhettinger for commit 291ed52 🤖

If you want to schedule another build, you need to add the 🔨 test-with-buildbots label again.

@bedevere-bot bedevere-bot removed the 🔨 test-with-buildbots Test PR w/ buildbots; report in status section label Oct 27, 2023
@rhettinger rhettinger merged commit 7f9a99e into python:main Oct 27, 2023
@rhettinger rhettinger deleted the remove_classmethod_descriptor_chaining branch October 27, 2023 05:25
facebook-github-bot pushed a commit to facebookincubator/cinder that referenced this pull request Dec 22, 2023
@itamaro @facebook-github-bot
gh-89519 & gh-113157 (Remove classmethod descriptor chaining, depreca…
f508768 
…ted since 3.11)

Summary:
backport upstream PRs python/cpython#110163 and python/cpython#113233

upstream issues: python/cpython#89519 (Calling help executes classmethod property decorated methods) and python/cpython#113157 (Changed behavior of <instancemethod>.__get__ in Python 3.11)

upstream commits: [`7f9a99e8549b792662f2cd28bf38a4d4625bd402`](python/cpython@7f9a99e) and [`d058eaeed44766a8291013b275ad22f153935d3b`](python/cpython@d058eae)

Reviewed By: aleivag

Differential Revision: D52014322

fbshipit-source-id: 87de6d9587bd9cc49f053ca340adfc469b041f91
aisk pushed a commit to aisk/cpython that referenced this pull request Feb 11, 2024
@rhettinger @aisk
pythongh-89519: Remove classmethod descriptor chaining, deprecated si…
c63736d 
…nce 3.11 (pythongh-110163)
@0Hughman0 0Hughman0 mentioned this pull request Jul 9, 2024
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Glyphack pushed a commit to Glyphack/cpython that referenced this pull request Sep 2, 2024
@rhettinger @Glyphack
pythongh-89519: Remove classmethod descriptor chaining, deprecated si…
e3d33d5 
…nce 3.11 (pythongh-110163)
@chrisimcevoy chrisimcevoy mentioned this pull request Sep 20, 2025
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copybara-service bot pushed a commit to google/fiddle that referenced this pull request Jan 12, 2026
@oprypin @copybara-github
Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …
1b9fda6 
…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 855235679
@copybara-service copybara-service bot mentioned this pull request Jan 12, 2026
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copybara-service bot pushed a commit to google/fiddle that referenced this pull request Jan 12, 2026
@oprypin @copybara-github
Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …
67c2eb6 
…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 855235679
copybara-service bot pushed a commit to google/fiddle that referenced this pull request Jan 13, 2026
@oprypin @copybara-github
Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …
01c6891 
…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 855235679
copybara-service bot pushed a commit to google/fiddle that referenced this pull request Jan 13, 2026
@oprypin @copybara-github
Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …
803ea8e 
…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 855235679
copybara-service bot pushed a commit to google/fiddle that referenced this pull request Jan 15, 2026
@oprypin @copybara-github
Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …
1f05ce1 
…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 855235679
copybara-service bot pushed a commit to google/fiddle that referenced this pull request Jan 15, 2026
@oprypin @copybara-github
Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …
f459007 
…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 855235679
copybara-service bot pushed a commit to google/fiddle that referenced this pull request Jan 15, 2026
@oprypin @copybara-github
Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with …
3d956df 
…a new dedicated `AutoConfigClassMethod` descriptor.

This is necessary because Python 3.13 no longer recognizes descriptor chaining: python/cpython#110163

PiperOrigin-RevId: 856608179
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